Are your kids interested in magic? Probably they’re tired of the classical trick with the coin. So, let’s teach them how to make a propeller whirl and change its rotation by simply saying a magic word.
This could be a great chance to show how circular vibrations work and organize a magic show.
a wooden stick 3x2cm and 20cm long
two flat balsa laths 2mm thick and 3cm long
2 small nails
STEP 1: PIERCING
Draw a line with a pencil in the middle of the wooden stick. With a drill bit of 4mm, pierce a series of holes along the line. The distance between the holes must be 3mm.
STEP 2: CUTTING
With the saw, divide in two the wooden stick, following the holes.
Now, you’ve got two identical sticks with a notched side. Sandpaper the sticks and fix the balsa laths at the top of them with the nails.
STEP 3: WHIRLING
Grab one stick and start rubbing a pencil against the notched side. If you are patient, you will see the propeller starts whirling.
This movement is due to the stick’s vibration, which makes the propeller rotate
You can change the direction of the rotation with the position of your fingers. The most effective changes are brought by pressing against the pencil with the thumb and the index finger.
However, remember that what works for a person, could not get the same result for another.
So, while your magic propeller is rotating, choose a magic word and pronounce it, changing the position and the pressure of your fingers at the same time.
What are you waiting for? Let your children whirl their magic propeller and leave their friend open-mouthed!
Leave comments, do you find it easy to make? Still got doubts? Which magic word would you choose?
Translation: Rossana Caruso